1. Technical Field
The present invention relates to a solenoid valve for use mainly in a combustion apparatus.
2. Background Art
This kind of solenoid valve is conventionally provided with: a valve body; a moving core having connected to one end thereof the valve body; a guide tube having slidably inserted thereinto the moving core; a stationary core disposed in an inner periphery of an opposite end portion of the guide tube so as to face an opposite end of the moving core; a valve spring to urge (press or force) the moving core in a direction away from the stationary core; an electromagnetic coil disposed to enclose the guide tube; and a magnetic plate disposed on the opposite end of the guide tube, whereby the moving core is sucked to the stationary core by a magnetic force transmitted through the magnetic plate to the stationary core due to electric charging to the electromagnetic coil.
In order to enable to efficiently transmit the magnetic force from the magnetic plate to the stationary core, it is necessary to bring the surface of the stationary core, said surface lying opposite to (or facing) the magnetic plate, into contact with the magnetic plate. The surface in question is hereinafter also called “that surface of the stationary core which faces the magnetic plate.” This expression of “that . . . which” will make it clear that it is the “surface” (not the “stationary core”) that faces or lies opposite to the magnetic plate. As a solution, conventionally there is formed, in a part of that surface of the stationary core which faces the magnetic plate, a projection to penetrate through a perforation (through hole) that is formed in the magnetic plate. Such a tip portion of the projection as is protruding through the perforation is thereafter caulked so as to bring that surface of the stationary core which faces the magnetic plate into contact with the magnetic plate (see, for example, JP-A-2010-164104).
In this conventional example, however, the magnetic plate is pushed toward the electromagnetic coil when the tip portion of the projection is caulked. As a consequence, in case the caulking force is excessive, an undue compression load will be applied to the electromagnetic coil. There is therefore a possibility that a bobbin of the electromagnetic coil gives rise to deformation.